This proposal seeks to 1) quantitate the transfer of functional anti-herpes simplex virus (HSV) antibody-dependent cellular cytotoxicity (ADCC) antibody and ADCC epitope-specific antibody from mother to the term and preterm neonate; 2) determine the ontogeny of ADCC effector function in otherwise healthy, very preterm, preterm and term babies; and 3) measure ADCC leukocyte effector function in the uncommon neonate with ongoing HSV infection.